Currently, a dense deployment scenario for small cells in the LTE is an important scenario focused by standardization. In this scenario, a plurality of small cells operate in the same frequencies, their coverage areas overlap with each other, and significant interference may e generated among them when they are switched on simultaneously. However, such interference among the small cells may be reduced by using a semi-static or dynamic small cell on/off mechanism which may also save a power consumption of a base station.
In current standards, one small cell in an off state will not send an air-interface signal. Thus, a user equipment cannot detect synchronization signals from the small cell, nor can it measure information such as a reference signal received power (RSRP) of the small cell. If the UE discovers a signal quality of one small cell in the off state becomes better than that of the serving small cell, apparently, the UE should access the small cell in the off state. However, it is a problem to be solved that how the UE discovers the small cell in the off state.